Most of the computing and electronic devices manufactured nowadays use non-volatile memories for permanent storage of data. In these memories, data is not deleted even after the removal of the power supply. In other words, data once stored in these memories is retained irrespective of the status of the power supply to the memory.
The non-volatile memories include read only memories (ROMs), programmable read only memories (PROMs), erasable programmable read only memories (EPROMs), one-time-programmable (OTP) EPROMs, flash memories, and magneto-resistive read only memories (MRAM). A single non-volatile memory made up of one or more memory arrays, which in turn are made up of many electrically programmable memory cells.